[CBRD-20451] lf_freelist_claim: start lock-free transaction.

[ribram]

http://jira.cubrid.org/browse/CBRD-20451

Lock-free freelist claim: start a lock-free transaction (if it was not started yet) without incrementing transaction ID.

The scenario that otherwise creates problems:

1. t1: claim from freelist. no transaction is started. top of freelist available stack is read, next of top is read. thread is preempted before calling CAS on top with next.
2. t2: claim top from freelist available stack.
3. other transactions claim other entries from stack.
4. t2: retire claimed entry back to freelist. Decide to also transport the element. Since t1 has no transaction, the entry can be transported and added back to top of available stack. However, this time next has a different value.
5. t1: swap top with old next value. Since the old top has been recycled, the operation is successful. However, the freelist is now broken!

Special thanks to @rimio.

[eseokoh]

@ribram

Great catch!
Thank you.

@rimio

Great thanks for your help.